Control apparatus for a water supply system

ABSTRACT

A control apparatus for a water supply system having a motor operated pump for pumping water through a delivery line to one or more valved outlets. The control apparatus includes a pressure switch responsive to the pressure in the delivery line and operable at preselected upper and lower pressure limits to respectively stop and start the pump motor, and a valve which regulates flow from the pump to the delivery line and is operated by a pneumatically loaded diaphragm responsive to the pressure in the delivery line to maintain the pressure in the line substantially constant at a value intermediate the upper and lower pressure limits during normal flow from the delivery line, with a bypass for passing a restricted flow of fluid into the delivery line, when the flow from the delivery line is shut off and the valve is closed, to increase the pressure in the delivery line and operate the switch to shut off the pump motor. The diaphragm also functions as a small expansion chamber to limit the frequency at which the control apparatus will cycle the pump motor, when water is drawn from the delivery line at a rate below the bypass rate, and provision is made for controlling the expansion and contraction of the diaphragm in a manner to effect a rapid increase in pressure into the delivery line to shut off the pump motor, when flow from the delivery line is terminated.

United States Patent [1 1 Deters Jan. 1, 1974 CONTROL APPARATUS FOR AWATER SUPPLY SYSTEM [75] Elmer M. Deters, Muscatine, Iowa Inventor:

Red Jacket Manufacturing Company, Davenport, Iowa Filed: Oct. 24, 1972Appl. No.: 300,211

Assignee:

References Cited UNITED STATES PATENTS 8/1963 Johnsen 417/44 X 10/1963Johnsen...' 417/44 X Primary Examiner-Carlton R. Croyle AssistantExaminer-Richard Sher Attorney-Vernon J. Pillote [57] ABSTRACT A controlapparatus for a water supply system having a motor operated pump forpumping water through a delivery line to one or more valved outlets. Thecontrol apparatus includes a pressure switch responsive to the pressurein the delivery line and operable at preselected upper and lowerpressure limits to respectively stop and start the pump motor, and avalve which regulates flow from the pump to the delivery line and isoperated by a pneumatically loaded diaphragm responsive to the pressurein the delivery line to maintain the pressure in the line substantiallyconstant at a value intermediate the upper and lower pressure limitsduring normal flow from the delivery line, with a bypass for passing arestricted flow of fluid into the delivery line, when the flow from thedelivery line is shut off and the valve is closed, to increase thepressure in the delivery line and operate the switch to shut off thepump motor. The diaphragm also functions as a small expansion chamber tolimit the frequency at which the control apparatus will cycle the pumpmotor, when water is drawn from the delivery line at a rate below thebypass rate, and provision is made for controlling the expansion andcontraction of the diaphragm in a manner to effect a rapid increase inpressure into the delivery line to shut off the pump motor, when flowfrom the delivery line is terminated.

6 Claims, 6 Drawing Figures 545 b 34a 3a 8 5 33 51c 2a 24a. 314 5/8 Z//24 I u /16b 7 7 g 1 r L 31b 11 25 5 -4 t E Z .l

CONTROL APPARATUS FOR A WATER SUPPLY SYSTEM BACKGROUND OF THE INVENTIONThe present invention relates to water system control apparatus of thetype having a pressure switch responsive to the pressure in the deliveryline for starting and stopping the pump; a valve for controlling flowinto the delivery line; a pressure loaded diaphragm responsive to thepressure in the delivery line for controlling operation of the valve toregulate the pressure in the line at a value below the upper switchoperating pressure during normal flow from the line; and a bypass topass a restricted flow into the delivery line when flow from the line isterminated to cause the pressure in the line to build up above theregulated pressure and operate the pressure switch to shut off the pump.In such control apparatus, the pump will cycle on and off if the flowfrom the delivery line is less than the bypass rate. It is accordinglydesirable to make the bypass very small to minimize the flow rate belowwhich cycling can occur. However, under some conditions, such as due toan improperly closed outlet valve or other leakage from the deliveryline, very low flows can occur from the line and, in order to preventrapid cycling of the pump motor with the consequent danger of motorfailure at such low flow rates, it is also desirable to provide anexpansion chamber to maintain the pressure in the delivery line abovethe lower switch operating pressure for a time interval after stoppingthe pump.

One such water system control apparatus is disclosed in the U. S. Pat.to O. F. Johnsen, No. 3,100,505. In the control apparatus disclosed inthat patent, the diaphragm is arranged to move away from the valvemember when the valve member closes and the pressure in the lineincreases above the regulated pressure to provide a small expansionchamber. An objection to that system was that the restricted flow offluid through the bypass caused a slow buildup in pressure in thedelivery line so that there was a substantial time lapse betweenstopping of discharge from the delivery line and stopping of the pump.This is particularly serious at the very low flow rates from thedelivery line at which the control apparatus causes the motor pump tocycle on and off. This objection was recognized by the patentee and inthe subsequent U. S. Pat. to O. F. .Iohnsen, No. 3,106,894 there isdisclosed a modified control apparatus utilizing a primary valve with arestricted bypass as well as a secondary valve arranged to open afterthe primary valve is closed, to effect rapid filling of the expansionchamber. While the construction shown in this last-mentioned patentdecreases the time lapse between termination of flow and stopping of thepump, it does increase the complexity of the valve apparatus and thecost of making the same.

The present invention relates to improvements in water system controlapparatus of the type described. Various important objects of thepresent invention are to provide an improved water system controlapparatus which is operative to maintain a substantially constantpressure in the delivery line during normal flow from the line; whichavoids repeated cycling of the pump motor on and off during draw ofwater from the line, except at very low draw rates; which cyclicallyoperates the pump motor on and off at the very low draw rates in amanner to 'maintain the pump on-time short as compared to the pumpoff-time; and which minimizes the delay between termination of draw andshut-off of the motor pump; which is simple and economical inconstruction and reliable in operation.

These, together with other objectsand advantages of this invention willbe apparent from the following detailed description and the accompanyingdrawings wherein:

FIG. I is a fragmentary sectional view of a water system installationembodying the control apparatus of the present invention;

FIG. 2 is a sectional view through the valve apparatus illustrating thesame in a closed position;

FIG. 2A is a graph illustrating the relationship between the deliverytime pressure and the diaphragm travel;

FIG. 3 is a sectional view through the valve apparatus illustrating thesame in a moved position;

FIG. 4 is a fragmentary sectional view taken on the plane 4-4 of FIG. 3;and

FIG. 5 is a graph illustrating the change of pump pressure and deliveryline pressure with flow from the delivery line.

The control apparatus of the present invention is arranged for use in awater supply system having a pump 10, such as a centrifugal pump or jetpump, driven by an electric motor 1 1. As shown in FIG. 1, the pump hasits inlet 10a connected to a water supply source such as a well 12 andits outlet 10b connected to a fluid delivery line 13 having one or morevalved outlets 14. The control apparatus in general includes a pressureswitch 16 which is operated in response to the pressure in the deliveryline to start and stop the pump motor, and a valve apparatus 17connected to control of flow from the pump to the delivery line. Asdiagrammatically shown in FIG. 1, the pump motor 11 is connected throughlines 18 to a source of electrical power and is connected through lines19 to the pressure switch 16 to be energized under the control of thepressure switch. The pressure switch 16 is of the type commonly used inpressure tank type water systems and which includes a pressureresponsive actuator 16a that is operative at a preselected lowerdelivery line pressure, for example 30 p.s.i., to close motor controlcontacts 16b and start the pump motor 11 and which maintains the pumpmotor 11 energized until the delivery line pressure rises to apreselected upper pressure limit, for example 50 p.s.i., at which timethe pressure switch opens the motor control contacts and stops the pumpmotor. Such pressure switches which operate to start and stop the pumpat preselected upper and lower pressure limits are well known andfurther detailed illustration or description is deemed unnecessary.

The valve apparatus 17 is best shown in FIGS. 2 and 3 and includes avalve body having an inlet chamber 21 adapted for connection as by athreaded inlet passage 22 to the pump discharge, an outlet chamber 23adapted for connection as by a threaded outlet passage 24 to thedelivery line 13, and a valve seat 25 interme diate the inlet and outletchambers. The valve body also has a diaphragm bowl 26 coaxial with thevalve seat and communicating with the outlet chamber 23. The pressureswitch 16 is connected for operation in response to the pressure in thedelivery line 13 and, conveniently, the valve body is provided with apassage 28 that communicates with the outlet chamber 23 and hence withthe delivery line, and which is adapted for connection as by a threadedfitting 29 to the pressure switch 16 to enable mounting the pressureswitch on the valve body as shown in FIG. 1.

A valve member 31 is provided to control flow through the orifice and isconnected through a stem 32 to the central portion of a diaphragm 33that is peripherally attached to the diaphragm bowl and which has oneside exposed to the fluid pressure in the outlet chamber and hence tothe pressure in the delivery line. A pressure bell 34 is attached to thevalve body at the other side of the diaphragm and is pneumaticallycharged to apply pressure to the diaphragm in opposition to the waterpressure in the outlet chamber. The diaphragm is arranged to controlmovement of the valve member relative to the valve seat to maintain thepressure in the delivery line at a relatively constant value below theupper switch operating pressure during normal draw of water from thesystem, and a bypass 31a is provided to pass a restricted flow of waterinto the delivery line when flow from the line is terminated to causethe pressure in the line to build up above the regulated pressure andoperate the pressure switch to shut off the pump. If water leaks or iswithdrawn from the delivery line at flow rates below the bypass rate,the pressure switch will cycle the pump motor on and off and thediaphragm is accordingly arranged to also function as a small expansionchamber to control the rate at which the system will cycle at very lowdraw rates. As shown, a charging valve 35, conveniently of the type usedon rims of tubeless tires, is provided in the bell 34 for charging thebell to a preselected pressure. For example, the pressure bell 34 ischarged to a pressure such that the valve member will seat when thepressure in the outlet chamber reaches a preselected pressure such as 40p.s.i. which is intermediate the upper and lower switch operating limitswhich may, for example, be 50 and p.s.i. respectively. When the pump isoperating and water is being withdrawn from the system at rates abovethe bypass rate, the diaphragm will move the valve member relative toits seat to variably throttle the flow through the seat and regulate thepressure in the delivery line at a pressure of about 40 p.s.i., andsubstantially below the upper switch operating pressure so as to preventshutoff of the pump motor during normal draw of water from the line.However, when the flow from the delivery line is terminated or throttledbelow the bypass rate, the diaphragm will move the valve member to itsseated position at about 40 p.s.i. and the bypass 31a then operate s topass a restricted flow of water from the inlet chamber into the outletchamber to raise the pressure in the outlet chamber above the 40 p.s.i.valve seating pressure and up to the upper switch operating pressure.

It is desirable to maintain the delivery line pressure during normaldraw from the delivery line sufficiently below the upper switchoperating pressure to prevent spurious operation of the pressure switchdue to pressure surges in the delivery line. However, it is alsodesirable to minimize the time lapse between termination of flow fromthe delivery line and stopping of the pump motor. In accordance with thepresent invention, a diaphragm stop plate 36 is fixed to the pneumaticbell 34 and positioned to extend closely adjacent the diaphragm 33 whenthe valve member 31 reaches its seated position, so as to limit furtherexpansion movement of the diaphragm after the valve member has reached aseated position whereby the restricted flow of fluid through the bypass31a produces a relatively rapid change in pressure from the regulatedpressure of 40 p.s.i. to the upper switch operating pressure of 50p.s.i. It is necessary to assure that the valve member is seated beforeexpansion movement of the diaphragm is stopped, and the stop plate isaccordingly positioned so as to have only a slight clearance above thediaphragm when the valve member initially reaches a seated position.

The valve member 31 operates to regulate flow through the orifice in arelatively small portion of its overall stroke as it moves from theseated position shown in FIG. 2 to a fully opened position as shown inFIG. 3 and in response to a relatively small change in pressure in theoutlet chamber at the underside of the diaphragm. For example, asgraphically illustrated in FIG. 2A, the diaphragm will move from theposition D at which the valve member 31 is seated when the pressure inthe outlet chamber is at a pressure Pr such as 40 p.s.i. and, as thepressure in the outlet chamber decreases, the diaphragm will movedownwardly and fully open the valve member when the diaphragm reaches asecond position designated D at a pressure Pr such as 37 or 38 p.s.i.Thus, when the pump is operating, the pump discharge pressure will varyas indicated by the pressure-flow curve Pd in FIG. 5. However, when theflow from the delivery line is above the bypass rate, the diaphragm 33will operate the valve member to throttle flow to the delivery line andmaintain the delivery line pressure substantially constant in a rangebetween Pr when delivery line flow is just above the bypass rate andpressure Pr when the flow from the delivery line equals full pump flowat that pressure and valve member 31 is in its fully open position asshown in FIG. 3.

When the flow from the line is shut off, the bypass passes a restrictedflow of water, for example at a rate of about one-tenth gallon perminute or less, into the outlet chamber. The diaphragm stop plate ispositioned closely adjacent the diaphragm when it is in position D, soas to limit further expansion movement of the diaphragm. Accordingly,the bypass flow, even though at a very low flow rate, causes thepressure in the outlet chamber to rapidly build up, for example in about3 to 5 seconds after draw is terminated, from the pressure Pr to theupper switch operating pressure S to stop the pump motor.

As noted above, the control apparatus will cause the pump motor to cycleon and off if water leaks or is drawn from the delivery line at a ratebelow the bypass rate. Rapid cycling of the pump motor on and off isobjectionable and can result in overheating and failure of the motor.The control apparatus is arranged to delay restarting of the pump aftershutoff for a minimum time interval which is large as compared to thetime interval required to buildup the pressure in the line when themotor is restarted, so that even under the most adverse conditions inwhich the pump motor is cycled on and off, the motor on-time is short ascompared to the motor off-time. For this purpose, the diaphragm 33 isarranged to also function as a small expansion chamber which operates tomaintain the pressure in the delivery line above the lower switchoperating pressure S, for at least a minimum time interval afterstopping the pump, in the event there is leakage or drawing of fluidfrom the delivery line at a very low rate below the rate of flow throughthe restricted bypass 31a. The diaphragm bowl 26 is spaced below thediaphragm stop plate 36 a distance substantially greater than the strokeof the valve member necessary to move it between its seated and itsfully opened positions, and such that the diaphragm displaces a quantityof water which is sufficiently large as compared to the bypass rate todelay any decrease in pressure in the delivery line after stopping ofthe pump, which may becaused by leakage or drawing of water from theline at a rate below the bypass rate for a minimum time interval whichis long as compared to the time required for the pump to build thepressure back up to stop the motor. In the embodiment illustrated, thediaphragm bowl 26 is spaced from the stop plate a distance such that thediaphragm displaces about one-twentieth of a gallon of water as it movesfrom position D to position D against the bowl, and the bypass 31a isarranged to restrict the flow to about one-tenth gallons per minute orless. Under leakage conditions of one-tenth gallons per minute from thedelivery line, the diaphragm would maintain the delivery line pressureabove the lower switch operating pressure S (30 p.s.i.) for at least 30seconds and longer at lower leakage rates. However, when the pump is restarted, it rapidly refills the expansion chamber before the valve seatsat pressure Pr and the pressure in the outlet chamber thereafter rapidlybuilds up to the upper switch operating pressure S in a relativelyshorter time interval, of about 3 to 5 seconds.

The volume of the pressure bell above the stop plate is madesubstantially larger than the volume displaced by the diaphragm as itmoves from the stop plate to the diaphragmbowl so that the change inpressure in the outlet chamber from Pr, to P as the diaphragm moves fromposition D adjacent the stop plate to position D at the diaphragm bowl,is a small percentage of the regulated pressure Pr,. For example, in thedisclosed valve apparatus, the volume of the pressure bell above thestop plate 36 is about five times the volume of the displacement of thediaphragm 33 as it moves between the stop plate and the diaphragm bowl.Thus only a relatively small decrease in pressure, of the order of 5 to7 p.s.i. from the normal regulated pressure of about 40 p.s.i. willcause the diaphragm to move through its full stroke. Moreover, thischange in pressure is small as compared to the differential between theupper and lower switch operating pressures S, and S,.

The valve seat 25 and valve member 31 are preferably of the typeillustrated in the drawings and in which the valve seal comprises aresilient inwardly facing seat and the valve member is formed with aperipheral valve face seat and the valve dimensioned to be slidablyreceived in the seat. In the embodiment shown, the seat comprises anannular body of resilient material such as plastic or rubber positionedin an annular recess in the valve body and preferably having adownwardly opening groove to provide an inner resilient lip portionwhich forms the inwardly facing valve seat. The valve member 31 has itslower end portion formed with a cylindrical outer periphery 31bdimensioned to be slidably received in the inwardly facing seat and thebypass comprises a small notch or a groove 31a in the cylindricalportion dimensioned to pass the restricted flow of fluid from the inletchamber to the outlet chamber, when the valve member is seated. In orderto reduce chattering of the valve member as it approaches its seatedposition, particularly at high pressures, the valve member is preferablyformed with a second valve portion 310 having a cross-section slightlysmaller than the cylindrical valve portion 31b so as to throttle flowthrough the orifice before the cylindrical valve portion reaches itsseated position. The second valve portion can conveniently comprise acontinuation of the cylindrical lower portion with a flattened area 31dat one side providing a reduced flow passage when the second valveportion extends into the orifice. The valve memher is arranged to beself-centering in the valve seat and has an outwardly flaring upper face31a.

The valve member is formed rigidly with the stem 32 and the stem isattached to the diaphragm 33 for movement as a unit with the diaphragm.In order to minimize possible leakage, the diaphragm is made imperforateand attached to the stem by integral plugs 3311 that extend throughopenings in a diaphragm mounting plate 38. The diaphragm mounting plateis attached to the upper end of the stem as by a fastener andadditionally functions to reinforce the central portion of thediaphragm.

The diaphragm isformed with an integral thickened rim 33b around itouter periphery which is interposed between a flange 26a on thediaphragm bowl and an outwardly extending flange 34a on the lower end ofthe bell, to seal the'interface between the diaphragm, the valve bodyand the bell. The bell :is preferably formed with a depending lip 34bwhich is; arranged to engage the flange on the diaphragm bowl to controlcompression of the thickened rim on the diaphragm when the pressure bellis fastened to the diaphragm bowl by clamp bolts 39. The periphery ofthe stop plate 36 is interposed between the flange 34a on the pressurebell and the upper side of the diaphragm, inwardly of the raised rim 33bon the diaphragm.

From the foregoing it is thought that the construction and operation ofthe control apparatus will be readily understood. For the purpose ofdescribing the operation, it will be assumed that the control apparatusis initially in the position shown in FIG. 2 and that the pressure inthe delivery line has built up to the upper switch operating pressure Sof 50 p.s.i. and that the pump is stopped. If one of the outlet valves14 is opened to draw water from the delivery line, the pressure in thedelivery line and outlet chamber will rapidly decrease to the lowerswitch operating pressure S, (30 p.s.i.) and start the pump. Thepressure in the delivery line will then build up to the operatingpressure range of about 37 to 40 p.s.i. and the diaphragm 33 will movethe valve member 31 upwardly toward the valve seat 25 to variablythrottle the flow through the seat and maintain the delivery linepressure substantially constant independent of the pump dischargepressure. As the flow from the delivery line is decreased, the valvemember moves upwardly and reaches its seated position at about 40 p.s.i.At that time, flow through the seat is shut off except for therestricted bypass flow through bypass passage 31a. Since the diaphragmstop plate 36 is positioned closely adjacent the diaphragm when thevalve member is seated, only a relatively small quantity of fluid needsto flow into the outlet chamber to cause the diaphragm to expandslightly into firm engagement with the stop plate. At that time, furtherexpansion of the diaphragm chamber is stopped and the pressure in thediaphragm chamber and delivery line builds up rap idly as shown in FIG.2A from Pr, to the upper switch operating pressure S of about 50 p.s.i.,to thereby stop the pump motor. Thus, during normal draw of water fromthe delivery line, the diaphragm operates the valve member to preventthe pressure in the delivery line from building up to the upper switchoperating pressure so that the pump operates continuously during normaldraw, and the pump operation is terminated shortly after termination offlow from the delivery line. If fluid leaks or is withdrawn from thedelivery line at a very low rate below the bypass rate, the controlapparatus will cycle on and off. However, the diaphragm 33 alsofunctions as a small expansion chamber which is operative to maintainthe pressure in the delivery line above the lower switch operatingpressure under leakage conditions, for a time interval to preventexcessively rapid cycling of the motor.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

1. A control apparatus for a water system having a motor operated pumpfor pumping water through a delivery line to one or more valved outlets,the control apparatus including a valve body having an inlet chamberadapted for connection to a pump and an outlet chamber adapted forconnection to a delivery line of a water system and a valve seatintermediate the inlet and outlet chambers, pressure operated motorcontrol switch means responsive to the pressure in said outlet chamberfor energizing the pump motor when the pressure in the outlet chamberreaches a selected lower switch operating pressure and for de-energizingthe pump motor when the pressure in the outlet chamber reaches aselected upper switch operating pressure, said valve body having adiaphragm bowl in open communication with said outlet chamber andcoaxial with said valve seat and a diaphragm peripherally attached tosaid diaphragm bowl and extending across the bowl to define an expansionchamber therewith, a valve member in said inlet chamber cooperable withsaid seat for controlling flow therethrough, the valve member having astem extending through the seat and engageable with the diaphragm formovement into and out of a seated position under the control of saiddiaphragm, a pneumatic pressure bell attached to said diaphragm bowl atthe side opposite said expansion chamber and pneumatically charged toapply pressure to the diaphragm in opposition to the fluid pressure inthe expansion chamber and such as to allow seating of the valve memberwhen the pressure in the outlet chamber rises to a preselected valueintermediate said upper and lower switch operating pressures, and bypassmeans for passing a restricted flow of water from the inlet chamber intothe outlet chamber when the valve member is seated, the improvementcomprising: a diaphragm stop plate fixed to said bell and shaped toextend closely adjacent the diaphragm when the pressure in the outletchamber rises to said preselected value at which the valve member isseated for limiting expansive movement of the diaphragm whereby therestricted flow of water from the inlet chamber through the bypasscauses the pressure in the outlet chamber to rapidly build up to saidupper switch operating pressure, said valve member being movable by saiddiaphragm from a seated position when the diaphragm engages saiddiaphragm stop plate to a fully open position when the diaphragm hasmoved a preselected distance away from the stop plate, said diaphragmbowl being spaced from said stop plate a distance substantially greaterthan said preselected distance to allow continued contraction of saiddiaphragm chamber after the valve member has moved to its fully openposition, whereby said bowl engages the diaphragm to limit contractionof the expansible chamber only after the diaphragm has displaced aselected volume of water, the volume of said pressure bell above thediaphragm stop plate being substantially larger than said volume ofwater displaced by said diaphragm as it moves between said stop plateand said diaphragm bowl and such that the pressure change in the outletchamber necessary to move the diaphragm between the stop plate anddiaphragm bowl is small as compared to the differential between saidupper and lower switch operating pressures.

2. A control apparatus according to claim 1 wherein said valve member,valve stem and diaphragm are fixedly interconnected for movement as aunit.

3. A control apparatus according to claim 2 wherein said stem has arigid diaphragm mounting plate attached thereto and having openingstherein, said diaphragm being imperforate and having integral headedprotuberances extending through said openings in the mounting plate toattach the diaphragm to the mounting plate and valve stem.

4. A control apparatus according to claim 2 wherein said valve seatcomprises an annular inwardly facing seat of resilient material, saidvalve member having a substantially cylindrical valve portiondimensioned to be slidably received in said inwardly facing seat, saidbypass means comprising a notch in said cylindrical valve portionarranged to pass water from the inlet chamber to the outlet chamber whenthe valve member is seated.

5. A control apparatus according to claim 2 wherein said valve seatcomprises an annular inwardly facing seat of resilient material, saidvalve member having a substantially cylindrical valve portiondimensioned to be slidably received in said inwardly facing seat, saidbypass means comprising a notch in said cylindrical valve portionarranged to pass water from the inlet chamber to the outlet chamber whenthe valve member is seated, said valve member having a secondsemicylindrical valve portion on the side of said cylindrical valveportionadjacent said seat to throttle flow through said inwardly facingseat when said second valve portion extends into said seat to a valueintermediate said restricted flow and full flow throughthe valve.

6. A control apparatus according to claim 1 wherein said diaphragm hasan integral raised rim extending around the outer periphery thereof,said pressure bell having a peripheral mounting flange overlying saidraised rim on the diaphragm and fastened to the diaphragm bowl to sealthe periphery of the diaphragm to the bowl and pressure bell, saiddiaphragm stop plate having the periphery thereof interposed between thediaphragm and the mounting flange on the pressure bell inwardly of saidraised rim on the diaphragm.

1. A control apparatus for a water system having a motor operated pumpfor pumping water through a delivery line to one or more valved outlets,the control apparatus including a valve body having an inlet chamberadapted for connection to a pump and an outlet chamber adapted forconnection to a delivery line of a water system and a valve seatintermediate the inlet and outlet chambers, pressure operated motorcontrol switch means responsive to the pressure in said outlet chamberfor energizing the pump motor when the pressure in the outlet chamberreaches a selected lower switch operating pressure and for de-energizingthe pump motor when the pressure in the outlet chamber reaches aselected upper switch operating pressure, said valve body having adiaphragm bowl in open communication with said outlet chamber andcoaxial with said valve seat and a diaphragm peripherally attached tosaid diaphragm bowl and extending across the bowl to define an expansionchamber therewith, a valve member in said inlet chamber cooperable withsaid seat for controlling flow therethrough, the valve member having astem extending through the seat and engageable with the diaphragm formovement into and out of a seated position under the control of saiddiaphragm, a pneumatic pressure bell attached to said diaphragm bowl atthe side opposite said expansion chamber and pneumatically charged toapply pressure to the diaphragm in opposition to the fluid pressure inthe expansion chamber and such as to allow seating of the valve memberwhen the pressure in the outlet chamber rises to a preselected valueintermediate said upper and lower switch operating pressures, and bypassmeans for passing a restricted flow of water from the inlet chamber intothe outlet chamber when the valve member is seated, the improvementcomprising: a diaphragm stop plate fixed to said bell and shaped toextend closely adjacent the diaphragm when the pressure in the outletchamber rises to said preselected value at which the valve member isseated for limiting expansive movement of the diaphragm whereby therestricted flow of water from the inlet chamber through the bypasscauses the pressure in the outlet chamber to rapidly build up to saidupper switch operating pressure, said valve member being movable by saiddiaphragm from a seated position when the diaphragm engages saiddiaphragm stop plate to a fully open position when the diaphragm hasmoved a preselected distance away from the stop plate, said diaphragmbowl being spaced from said stop plate a distance substantially greaterthan said preselected distance to allow continued contraction of saiddiaphragm chamber after the valve member has moved to its fully openposition, whereby said bowl engages the diaphragm to limit contractionof the expansible chamber only after the diaphragm has displaced aselected volume of water, the volume of said pressure bell above thediaphragm stop plate being substantially larger than said volume ofwater displaced by said diaphragm as it moves between said stop plateand said diaphragm bowl and such that the pressure change in the outletchamber necessary to move the diaphragm between the stop plate anddiaphragm bowl is small as compared to the differential between saidupper and lower switch operating pressures.
 2. A control apparatusaccording to claim 1 wherein said valve member, valve stem and diaphragmare fixedly interconnected for movement as a unit.
 3. A controlapparatus according to claim 2 wherein said stem has a rigid diaphragmmounting plate attached thereto and having openings therein, saiddiaphragm being imperforate and having integral headed protuberancesextending through said openings in the mounting plate to attach thediaphragm to the mounting plate and valve stem.
 4. A control aPparatusaccording to claim 2 wherein said valve seat comprises an annularinwardly facing seat of resilient material, said valve member having asubstantially cylindrical valve portion dimensioned to be slidablyreceived in said inwardly facing seat, said bypass means comprising anotch in said cylindrical valve portion arranged to pass water from theinlet chamber to the outlet chamber when the valve member is seated. 5.A control apparatus according to claim 2 wherein said valve seatcomprises an annular inwardly facing seat of resilient material, saidvalve member having a substantially cylindrical valve portiondimensioned to be slidably received in said inwardly facing seat, saidbypass means comprising a notch in said cylindrical valve portionarranged to pass water from the inlet chamber to the outlet chamber whenthe valve member is seated, said valve member having a secondsemicylindrical valve portion on the side of said cylindrical valveportion adjacent said seat to throttle flow through said inwardly facingseat when said second valve portion extends into said seat to a valueintermediate said restricted flow and full flow through the valve.
 6. Acontrol apparatus according to claim 1 wherein said diaphragm has anintegral raised rim extending around the outer periphery thereof, saidpressure bell having a peripheral mounting flange overlying said raisedrim on the diaphragm and fastened to the diaphragm bowl to seal theperiphery of the diaphragm to the bowl and pressure bell, said diaphragmstop plate having the periphery thereof interposed between the diaphragmand the mounting flange on the pressure bell inwardly of said raised rimon the diaphragm.